Lefty Max Squishy sound

My Lefty Max with less than 100 miles on it is making a Squishing sound on the rebound stroke. It's most noticeable after a rough downhill. Is the oil foaming? It hasn't lost any oil, in fact I topped it off and bled it to make sure. The manual says Golden Spectro 2.5W is stock fluid. Is this good oil? Could I have damaged rebound valving? Am I just paranoid???
The sound is exactly the sound of squeezing a soapy wet sponge, and it's only on the rebound, which is on top, which makes me think bubbles..

In what settings?

Originally Posted by dogwood

My Lefty Max with less than 100 miles on it is making a Squishing sound on the rebound stroke. It's most noticeable after a rough downhill. Is the oil foaming? It hasn't lost any oil, in fact I topped it off and bled it to make sure. The manual says Golden Spectro 2.5W is stock fluid. Is this good oil? Could I have damaged rebound valving? Am I just paranoid???
The sound is exactly the sound of squeezing a soapy wet sponge, and it's only on the rebound, which is on top, which makes me think bubbles..

i have a Max also. In the full rebound setting, mine makes a similar sound. So far, I have not been worried about it. Is it affecting the performance? Are you riding in cold weather? Can you hear it at speed, or only when stopped and cycling the suspension?

The sound lessens as I crank up the rebound. So far it is only affecting performance in that it's a distraction, but I've turned up the rebound further than I needed to before. Temps have been in the 50s. I hear it at speed and when just bouncing the front end.
Did your's always make the sound since it was new? I'm hoping someone will tell me to switch to Finish Line fork oil.

My Lefty Max with less than 100 miles on it is making a Squishing sound on the rebound stroke. It's most noticeable after a rough downhill. Is the oil foaming? It hasn't lost any oil, in fact I topped it off and bled it to make sure. The manual says Golden Spectro 2.5W is stock fluid. Is this good oil? Could I have damaged rebound valving? Am I just paranoid???
The sound is exactly the sound of squeezing a soapy wet sponge, and it's only on the rebound, which is on top, which makes me think bubbles..

Describing a sound in a letter is hard to do (to what extent and duration), but more than likely you have air in the fluid (and cause "foaming"). The valves in there are near bullet-proof so no worries there.

Are you sure the manual says 2.5W? Anyway, Golden Spectro is what is called a "synthetic blend" which means its 50% mineral and 50% synthetic. I prefer 100% synthetic and have had great results using Silkolene Pro RSF 5W. That is the only stuff I will ever use! Pure synthetics also are more linear in a wider range of temps.

If there is no air in the system, you should not hear a thing (even 1 pin-head sized bubble can cause noise and loss in dampening)

Thanks. I thought Golden Spectro was full synthetic, I definitely want full synthetic. I'll order some and until it arrives I'll be practicing bleeding. I do it just like the manual says but it doesn't say how much cycling is necessary. It also seems like I could cycle it more thouroughly if I remove the spring, but the manual doesn't say to.

FWIW: I have made a narrow tray and fill it with 1QT of fork fluid....I cycle and assemble the cartridge while its submerged. Just make 100% sure the exterior is perfectly clean so you can reuse what is left in the tray.

I ordered a bottle of Finish Line 2.5W and also a bottle of 5W. But, for this change I just put in some old RockShox semi synthetic 5W that I had laying around. I'll let this cheap stuff rinse out any more particles that might be in there, and at the same time see if I like 5W better. In a few days I'll put the synthetic in and blend to what I think is best after a couple rides on this 5W.

As for the amount used. Stock it hold @ 175cc., but the compression damper, the one attached to the bottom cap, is wrapped with a piece of urethane foam that is held on with 3 zip ties. It's just wrapped around the shaft between the bottom cap and the stationary valve. I think removing it would double the oil volume which would keep the oil from ever overheating.

There was a lot of aluminum particles suspended in the old oil, enough to make the oil opaque.

Hummm......

There are no parts in the shock that make any metal-to-metal contact. They are isolated by o-rings or teflon seals. If the particles are really aluminum pieces, expect to hear the noise soon (unless it was particles left from a prior re-build).

The reason why it was opaque was due to the heat...induced from having air in the system.

I'm not too worried about the particles. They're more like dust, probably left over from manufacture. I left the old oil in a bowl overnight to see how much settled out. only a bit of it settled to the bottom, the oil was still murky. I think you're right that it had overheated, that's why I may remove that foam if it won't void the warranty.